Question

based on this article skin could be approximatly detected using hsv color space and taking hue range between 6 and 38.

i tried to use some combination of cvThreshold, in particular i thought this could be the right way:

cvThreshold(planeH, planeH, 38, UCHAR_MAX, CV_THRESH_TRUNC);
cvThreshold(planeH, planeH, 6, UCHAR_MAX, CV_THRESH_BINARY_INV);

but it does not work.
some help?

Answer 1

I believe the function you are really after is the cvInRange function. This function allows you to specify multiple intervals simultaneously.

For example,

CvMat* skinMask = cvCreateMat(...);
cvInRange(hsvImage, CvScalar(6, loS, loV), CvScalar(38, hiS, hiV), skinMask);

Where loS, loV, hiS, hiV are the lower and upper bounds of the S and V channels respectively.

Here is another one of my answers using inRange. If you can use the C++ interface, I would recommend that over the C interface as it has more features and is the actively maintained side of OpenCV going forward.